对25℃不同总铁浓度时Fe‐H2 O体系可能存在的组分进行了热力学分析,计算了各溶解组分的浓度,运用浓度比较法为判据,确定液相和液相、液相和固相以及各固相之间的分界线,绘制了水体中不同浓度时 Fe‐H2 O体系溶解组分优势区域图和Pourbaix图。对比不同浓度优势区域图时发现,在一定温度和压力下,总铁浓度的大小对Fe3+, Fe(OH)2+,HFeO2和FeO2-的优势区域影响不大,但对Fe2+,HFeO2-,Fe(OH)+的优势区域影响明显。随着总铁浓度的减小和碱化程度的逐步加强, Fe(O H )2和Fe3 O4会发生一系列复杂的质子化和聚合作用。总铁浓度越高,多核组分Fe(s),Fe3 O4(s),Fe(OH)2(s)和FeOOH(s)的稳定区域越大,性质越稳定。
The predominance diagram of dissolved species and a Pourbaix diagram of the Fe‐H2 O system in water are studied at 25 ℃ by a concentration comparison method . The concentration of dissolved species , borderlines for liquid phases or solid phases and borderlines between the solid and solid phase are calculated on the basis of thermodynamic analysis and electrochemical analysis with a total Fe concentration of CT(Fe)=1.0 × 10-4 mol-L -1 and CT(Fe)=1.0 × 10-7 mol-L -1 . The predominance diagram of dissolved species and the Pourbaix diagram of the Fe‐H2 O system are then plotted . Comparisons between predominance diagrams for different iron concentration show that at a specific temperature and pressure the total concentration of iron has little effect on the stable predominance regions of Fe3+ , Fe(OH)2+ , HFeO2 and FeO2- .However ,these conditions have a remarkable effect on Fe2+ ,HFeO2-and Fe(OH)+ .A series of hydroxylation and polymerization reactions may occur with Fe (OH )2 and Fe3 O4 resulting in change the total concentration of iron and acidity . A higher total concentration of iron results in a more big area and stable for the species Fe(s) ,Fe3O4(s) ,Fe(OH)2(s)and FeOOH(s) .